The invention relates to a construction for a heddle frame which includes top and bottom frame slats each of which has a heddle rod attached thereto which supports heddles in the frame. The heddles include central thread eyes in which the individual warp yarn ends are held during shedding on the loom. The heddles are typically constructed of metal and are fastened to the heddle rod by means of end slots in which the heddle rod is received.
There is considerable wear and noise between the heddle rod and the end slots of the heddles during the rapid reciprocation of the heddle frame during shedding due to the space and play between the heddles and heddle rod as a tight fit is not possible. This play and wear therebetween become attenuated in heddle frames utilized on high speed shuttleless looms where the reciprocating motion during shedding occurs most rapidly. Because of the high speed performance and rapid lifting cycles during shedding, the frame must be as light in weight as possible without sacrificing structural integrity.
Typically, the frame slat is extruded from aluminum for light weightness. The heddle rod is about seven-eights of an inch in height and constructed from a hardened steel to reduce wear of the heddle rod. The heddle rod is normally riveted to the frame slat about every three and one-half inches along the length of the heddle rod which may be upwards to twelve feet. Maintaining the heddle rod straight across the frame slat during riveting is a time consuming problematic process. Furthermore, the rivet connections are susceptible to loosening in high speed operation which can lead to force attenuation and undamped vibrations resulting in parts failure. To extrude the heddle rod as one-piece with the frame slat results in wear problems since the soft aluminum material of the heddle rod would wear excessively in contact with the heddle slot.
It has been proposed in German Pat. No. 2,933,442 to make a one-piece frame slat and heddle rod constructed from a soft material to which is glued a hard steel rail covering.
It has been proposed in the prior art to construct a heddle rod from a lightweight fiber reinforced plastic bonded to a light weight frame constructed from aluminum or other light material (U.S. Pat. No. 3,754,577). It has also been proposed to apply a metal or ceramic plating to those regions of the heddle rods subjected to wear (British Pat. No. 1,308,326).
In U.S. Pat. No. 4,106,530, it has been proposed to cover a lightweight metal heddle rod with a synthetic plastic material which is resistant to impact and wear at the locations of impact with the heddle rod slot and to provide such a covering which can be replaced and renewed.
However, the various platings and coverings heretofore utilized in heddle rod constructions have not been entirely satisfactory and have left parts of the heddle rod uncovered and exposed to wear and noise. Retention of the various platings and coverings under high dynamic forces has also been a problem to which much attention need be given.
Accordingly, an important object of the present invention is to provide an improved heddle frame construction wherein connection problems in alignment and riveting of the heddle rod to the frame slat are virtually eliminated.
Another important object of the present invention is to provide a one-piece frame slat and heddle rod construction of a light material having improved wear characteristics.
Still another important object of the present invention is to provide a heddle rod having its wear surfaces reinforced with a covering having improved retention characteristics.
Still another important object of the present invention is to provide a wear and noise resistant heddle rod construction.